The Fenway Institute (TFI) of Fenway Community Health (FCH), collaborating with the Boston University School of Public Health (BUSPH) and the Inter-university Consortium for Political and Social Research (ICPSR), requests R21 developmental infrastructure funding in response to PAR-06-362. Our application addresses recommendations from a 1999 Demographic and Behavioral Science Branch review acknowledging the need to encourage cutting-edge research, the viability of geographically dispersed researchers, and smaller population research centers to fill critical research gaps such as the health of disparities populations. FCH was established 35 years ago to provide health care to neighborhood residents regardless of payment source and to respond to the newly acknowledged health-related needs of sexual and gender minorities. Fenway was the first community-based clinical site in New England to develop HIV/AIDS services and has been a site for more than 100 HIV research studies since 1984. FCH created TFI in 2000 to become a national center of excellence in lesbian, gay, bisexual and transgender (LGBT) health, naming as Co-Chairs the physician/clinical researcher who initiated the AIDS research program and a social scientist instrumental in the emerging national program for LGBT health. Permanent appointments are held by six active scientists who are resident at TFI for a portion of each week and 5 senior scientists from major universities who collaborate on studies. Population research methods are increasingly employed;scientists with permanent appointments all have experience adapting these methods to the study of LGBT health. With NICHD developmental infrastructure support, we can solidify the capacity to support an R24 population research center as a national center of excellence in LGBT health science. Our goals for the 5 years of developmental funding are to establish a public access research data archive at ICPSR, build a pipeline program at the BUSPH to train pre- and post-doctoral students, and provide a dedicated space with effective administrative, communications, and computing support as a community-based research home for leading scientists in the field of LGBT health. Our three signature areas are behavioral research on the sexual transmission of HIV, research on LGBT families and households, and demographic aspects of LGBT health, morbidity, disability, and mortality. Studies have shown that sexual and gender minorities have higher prevalence of life-threatening physical and mental health conditions, experience barriers to health care access, and face substantial threats to quality of life. We will conduct the research to fill critical knowledge gaps, providing a foundation for culturally competent treatment and behavior change models.